The present invention relates to techniques for a touch sensor device, a display device, an electronic equipment, and others.
Various types of electronic equipments and display devices such as smartphones have a touch sensor device (referred to also as a touch panel) mounted thereon as input means. As the touch sensor device, there is an electrostatic capacitance type touch sensor device. Examples of the touch sensor device include a touch sensor device having an exclusively-used touch sensor function, a display device with an externally attached type touch sensor or a cover integral type touch sensor, a display device with a touch sensor in which electrodes constituting a touch sensor function are incorporated in a display panel, and the like. The display device with an externally attached type touch sensor or a cover integral type touch sensor is referred to also as a display device with an on-cell type touch sensor. The display device with a touch sensor in which electrodes constituting a touch sensor function are incorporated in a display panel is referred to also as a display device with an in-cell type touch sensor. Moreover, as the display device with a touch sensor, there is a display device with a touch sensor in which an electrostatic capacitance type touch sensor device is applied to a liquid crystal display device (referred to also as a liquid crystal touch panel).
The electrostatic capacitance type touch sensor device is provided with drive electrodes (also referred to as transmission side electrodes) and detection electrodes (also referred to as reception side electrodes) as the electrodes constituting a touch sensor function. Units of touch detection are constituted by intersections in the pairs of the drive electrodes and the detection electrodes. For convenience of description, the units of touch detection are referred to as detection units. For example, on a surface serving as a touch detection area, a plurality of drive electrodes are disposed in parallel with one another in an in-plane horizontal direction, and a plurality of detection electrodes are disposed in parallel with one another in an in-plane perpendicular direction. The drive electrodes and the detection electrodes intersect with each other with a distance in a direction perpendicular to the surface of the touch detection area. A detection unit is constituted by a capacitance formed near the intersecting portion in the pair of each drive electrode and each detection electrode. On the surface of the touch detection area, a plurality of detection units are formed in a matrix pattern.
The touch sensor device has a circuit unit connected to the drive electrodes and detection electrodes. The circuit unit inputs a touch driving signal to the drive electrodes and detects a signal output from the detection electrodes through the detection units based on the signal. When the capacitance in a detection unit is changed by a touch of a conductor such as a finger to the surface of a touch detection area, the circuit unit detects the change of the capacitance as an electric signal. The touch sensor device detects the presence or absence and the position or the like of a touch to the touch detection area in the above-described manner.
The display device with an on-cell type touch sensor has, for example, a configuration in which a touch sensor device is externally connected to a front-surface side on which the display area of a liquid crystal display panel unit is formed. Alternatively, the display device with an on-cell type touch sensor has a configuration in which electrodes constituting a touch sensor function are integrally formed in a cover which is made of glass or a plastic material and attached to the front-surface side of a liquid crystal display panel unit.
The display device with an in-cell type touch sensor has, for example, a configuration in which at least either one of the drive electrodes and the detection electrodes corresponding to the electrodes constituting the touch sensor function, for example, the drive electrodes are incorporated in the liquid crystal display panel unit. The display device with an in-cell type touch sensor having this configuration is prepared by forming electrodes, in which common electrodes of the liquid crystal display device and the drive electrodes are integrated, on a TFT substrate serving as a first substrate structure and forming the detection electrodes on a color filter substrate serving as a second substrate structure.
As a driving method of the display device with an in-cell type touch sensor, for example, a method which carries out the driving while separating a display period for liquid crystal display function and a touch detection period for touch sensor function in terms of time is applied. This time-sharing driving method is advantageous in that influences of noise generated from the liquid crystal display panel unit during the display period for the liquid crystal display function are less likely to be given during the touch detection period for the touch sensor function.
As a prior-art example relating to the touch sensor device, there is Japanese Patent Application Laid-Open Publication No. 2010-72743 (Patent Document 1). In Patent Document 1, an electrostatic capacitance type touch sensor device and a display device with an in-cell type touch sensor are described. Patent Document 1 describes that a detection speed is improved without increasing the frequency at the time of touch driving for touch detection.